1. Field of the Invention
The present invention relates to a method for controlling the battery of a mild hybrid vehicle and, more specifically, to a method for determining a target State of Charge (SOC) of an energy storage device of a mild hybrid vehicle based on traffic conditions.
2. Description of the Prior Art
Vehicle manufacturers have made an effort to improve fuel economy and develop eco-friendly vehicles in response to the increase of social interest in rising oil prices and the environment, and hybrid systems that regenerate and use the deceleration energy of vehicles have emerged in order to satisfy this demand.
In the related art, in order to control the battery charging state of a hybrid vehicle, the compensation value for an engine torque is calculated from the output of a motor based on information, such as the State of Charge (SOC) of the battery, power of a low-voltage battery that supplies power to an electric field load side of the vehicle, a driving environment (an angle of inclination and external temperature), and the like, and then an operating point (an engine torque output point according to a current engine RPM) of an engine is finally determined based on the calculated compensation value.
However, the control method in the related art does not consider road/traffic conditions and accordingly, does not maximize a Stop and Go function that has a great effect of fuel economy improvement and a regenerative energy use function. For example, in cases where the battery charging state is maintained to be a single target SOC, the Stop and Go function cannot be sufficiently utilized in heavy traffic congestion. In contrast, maximum regenerative energy has to be used in road/traffic conditions that have a large regenerative quantity, but unnecessary engine power generation occurs in order to manage the battery, thereby increasing fuel consumption.
The related art document below discloses a technology of controlling Idle Stop and Go and behavior based on information transmitted from a traffic control center, but does not disclose a technical feature of the present invention wherein a target SOC of an energy storage device of a mild hybrid vehicle is adjusted based on a driving condition of a vehicle.